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Author name code: mihalas-weibel
ADS astronomy entries on 2022-09-14
author:Mihalas, Barbara
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Title: How may seismological measurements constrain parameters of
stellar structure?
Authors: Brown, T. M.; Christensen-Dalsgaard, J.; Mihalas, B. W.
1993ASPC...40..554B Altcode: 1993IAUCo.137..554B; 1993ist..proc..554B
No abstract at ADS
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Title: The Equation of State for Stellar Envelopes. IV. Thermodynamic
Quantities and Selected Ionization Fractions for Six Elemental Mixes
Authors: Mihalas, Dimitri; Hummer, D. G.; Mihalas, Barbara Weibel;
Daeppen, Werner
1990ApJ...350..300M Altcode:
The free-energy minimization technique in the form developed in the
preceding papers in this series is employed to evaluate thermodynamic
quantities and ionization fractions on a fine temperature and density
grid for six astrophysical mixtures of 15 elements. The mixtures
range from that appropriate to super-metal-rich stars, through solar
abundance, to that for extreme Population II objects. In this paper,
the results for solar abundances are summarized in a form that is
illustrative and which facilitates comparison with the results from
other equation of state calculations.
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Title: The Equation of State for Stellar Envelopes. III. Thermodynamic
Quantities
Authors: Daeppen, Werner; Mihalas, Dimitri; Hummer, D. G.; Mihalas,
Barbara Weibel
1988ApJ...332..261D Altcode:
The authors derive general formulae for the computation of the
thermodynamic properties of a partially ionized (and/or dissociated)
multicomponent gas in terms of second derivatives of the free energy
with respect to temperature, volume, and occupation numbers. For the
free energy used in previous work the authors give explicit analytical
expressions for all derivatives required to construct the thermodynamic
quantities. Representative results for several different thermodynamic
properties of a hydrogen-helium plasma with N(He)/N(H) = 0.10 are
presented as color plots.
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Title: Book-Review - Foundations of Radiation Hydrodynamics
Authors: Michalas, D.; Mihalas, B.; Kampfer, B.
1988AN....309..381M Altcode:
No abstract at ADS
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Title: Book-Review - Foundations of Radiation Hydrodynamics
Authors: Mihalas, D.; Mihalas, B. W.; Machado, M. E.
1986SoPh..103..409M Altcode:
No abstract at ADS
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Title: Solar waves and oscillations.
Authors: Brown, T. M.; Mihalas, B. W.; Rhodes, E. J., Jr.
1986psun....1..177B Altcode:
Contents: Theory of waves and oscillations (basic equations: full
hydromagnetic equations, linearized equations; waves: nonmagnetic waves,
magnetohydrodynamic waves; general properties of solar oscillations:
equations and spheroidal mode solutions, Cowling approximation,
asymptotic behavior of p- and g-mode frequencies, radial oscillations,
properties of nonadiabatic solutions, toroidal oscillations; excitation
and damping of solar pulsations: excitation and damping mechanisms,
mode lifetimes, stability of solar pulsation modes; detailed solutions
for frequencies and frequency splitting: effects of structure on
unperturbed frequencies, effects of rotation, effects of internal
magnetic fields; future theoretical needs). Observations (observational
techniques: diagnostics of spectrum lines, techniques for observing
oscillations and trapped waves; oscillations observed: observations
of 5 minute period p-mode oscillations, the 160 minute oscillation,
torsional oscillations, localized brightness oscillations; wave
observations; waves and oscillations in sunspots; future observational
needs). Oscillations as probes of the solar interior (direct method:
technique and results; inversion methods: technique and applications).
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Title: Book-Review - Foundations of Radiation Hydrodynamics
Authors: Mihalas, D.; Mihalas, B. W.; King, A.
1985Obs...105..238M Altcode:
No abstract at ADS
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Title: Book-Review - Foundations of Radiation Hydrodynamics
Authors: Mihalas, D.; Mihalas, B.
1985S&T....70..231M Altcode:
No abstract at ADS
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Title: Analysis and interpretation of synthetic time strings of
oscillation data.
Authors: Mihalas, B. W.; Christensen-Dalsgaard, J.; Brown, T. M.
1984sses.nasa..279M Altcode: 1984sss..conf..279M
Artificial strings of solar oscillation data with gaps and noise,
corresponding to the output of different spatial filter functions,
were analyzed. Peaks in the power spectrum are identified for values of
the degree l from 0 to 18, and rotational splitting is estimated. The
filters prove effective in facilitating identification of essentially
all the real peaks in the power spectrum. Estimates of peak frequencies
and amplitudes and rotational splitting frequencies are in reasonably
good agreement with the input values. Spurious peaks in autocorrelation
spectra correspond to the frequency spacing between power peaks with
the same order n, differing by one or two in the degree l.
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Title: Self-consistent radiation-hydrodynamic equations for stellar
oscillations. I - Nonlinear form
Authors: Mihalas, B. W.
1984ApJ...284..299M Altcode:
Using the correct comoving frame, or Lagrangian, equations of radiation
hydrodynamics derived by Castor and Buchler, earlier discussions of
radiation hydrodynamics in the nonequilibrium diffusion regime are
critically examined. Comparison of corresponding equations reveals a
fundamental conceptual error in previous treatments of the interaction
between stellar oscillations and the radiation field.
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Title: Wave Propagation in a Radiating Medium
Authors: Mihalas, B. W.
1984BAAS...16..947M Altcode:
No abstract at ADS
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Title: On the Propagation of Acoustic Waves in a Radiative Fluid
Authors: Mihalas, D.; Mihalas, B. W.
1984ApJ...283..469M Altcode:
No abstract at ADS
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Title: Foundations of radiation hydrodynamics
Authors: Mihalas, D.; Mihalas, B. W.
1984oup..book.....M Altcode:
This book is the result of an attempt, over the past few years, to
gather the basic tools required to do research on radiating flows
in astrophysics. The microphysics of gases is discussed, taking into
account the equation of state of a perfect gas, the first and second
law of thermodynamics, the thermal properties of a perfect gas, the
distribution function and Boltzmann's equation, the collision integral,
the Maxwellian velocity distribution, Boltzmann's H-theorem, the time
of relaxation, and aspects of classical statistical mechanics. Other
subjects explored are related to the dynamics of ideal fluids, the
dynamics of viscous and heat-conducting fluids, relativistic fluid flow,
waves, shocks, winds, radiation and radiative transfer, the equations
of radiation hydrodynamics, and radiating flows. Attention is given
to small-amplitude disturbances, nonlinear flows, the interaction of
radiation and matter, the solution of the transfer equation, acoustic
waves, acoustic-gravity waves, basic concepts of special relativity,
and equations of motion and energy.
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Title: Inferring Wave Motions: A Non-BOTE Problem
Authors: Mihalas, B. W.
1984ssdp.conf..235M Altcode:
Inferred phases are probably reliable for a very limited range of
physical situations. In other situations, the uncertainties in phase
arise from many effects, which the author tries to portray. Deducing
phases of propagating waves, and estimating uncertainties in those
phases, is a non-Back-Of-The-Envelope (non-BOTE) problem; "reasonable"
approximations can easily lead to incorrect conclusions.
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Title: On the propagation of acoustic waves in a radiating fluid
Authors: Mihalas, D.; Mihalas, B. W.
1983ApJ...273..355M Altcode:
The linearized Lagrangian radiation equations of Castor (1972) are
used in order to obtain a virtually complete and physically satisfying
view of acoustic wave dynamics in a radiating fluid. It is assumed
that the radiation field is quasi-static, all dynamical radiation
terms are ignored, and the Eddington approximation is applied. It is
noted that it would be useful to proceed with the complementary study
of the time evolution of initial disturbances.
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Title: Internal gravity waves in the solar atmosphere. II - Effects
of radiative damping
Authors: Mihalas, B. W.; Toomre, J.
1982ApJ...263..386M Altcode:
In the solar photosphere, temperature fluctuations associated
with acoustic-gravity waves may be rapidly smoothed by the transfer
mechanism of radiation between hotter and cooler regions. The present
investigation of the radiative effects on internal gravity waves takes
into account the parameterization of the radiative energy, employing the
Newtonian cooling approximation. A linear analysis of the propagation of
internal gravity waves is carried out in a model of the solar atmosphere
which is taken to be homogeneous in the horizontal coordinates. Linear
wave properties both with and without radiative cooling are summarized,
and the variation with height of energy fluxes and of nonlinearities
in the waves is discussed. Attention is given to the significance of
the obtained results in terms of energy balance in the chromosphere
and in relation to spectral line observations.
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Title: Internal gravity waves in the solar atmosphere. I - Adiabatic
waves in the chromosphere
Authors: Mihalas, B. W.; Toomre, J.
1981ApJ...249..349M Altcode:
The properties of adiabatic and linear internal gravity waves
propagating in a solar wind model are discussed, using nonlinearity
criteria unique to gravity waves to estimate wave-breaking heights. The
results are used to deduce information on the possible role of gravity
waves in the chromospheric energy balance. Maximum vertical velocity
amplitudes for gravity waves are estimated to be on the order of 2
km/sec or less, and maximum horizontal velocity amplitudes are less than
6 km/sec, with temperature perturbations as large as 1000-2000 K. It
is also estimated that gravity waves with an incident energy flux of
one million ergs/sq cm-sec can propagate upward to a maximum height
of 900-1000 km above the visible surface before nonlinearities lead
to wave breaking, while those with an energy flux of 100,000 ergs/sq
cm-sec can reach maximum heights of 1400-1600 km.
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Title: Internal Gravity Waves?
Authors: Mihalas, B.
1981siwn.conf...82M Altcode:
No abstract at ADS
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Title: Internal gravity waves in the solar atmosphere
Authors: Mihalas, Barbara Ruth Weibel
1979PhDT.......235M Altcode:
No abstract at ADS
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Title: Internal Gravity Waves in the Solar Atmosphere.
Authors: Mihalas, B. R.
1979PhDT.........9M Altcode:
Three aspects of the behavior of gravity waves in the solar
atmosphere are considered adiabatic propagation in the photosphere
and chromosphere; photospheric radiative damping of waves generated by
convection; and the effects of waves on spectral line profiles. The wave
propagation studies are carried out with linearized fluid equations in
a standard solar model. The fluid equations are reduced to a single
Schroedinger-type equation in the vertical velocity, which is solved
as a two-point boundary-value problem. Wave perturbations derived
from this solution are used in a line transfer code to study effects
of waves with varying parameters on spectra line profiles.
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Title: Two-dimensional radiative transfer. I. Planar geometry.
Authors: Mihalas, D.; Auer, L. H.; Mihalas, B. R.
1978ApJ...220.1001M Altcode:
Differential-equation methods for solving the transfer equation in
two-dimensional planar geometries are developed. One method, which uses
a Hermitian integration formula on ray segments through grid points,
proves to be extremely well suited to velocity-dependent problems. An
efficient elimination scheme is developed for which the computing time
scales linearly with the number of angles and frequencies; problems
with large velocity amplitudes can thus be treated accurately. A very
accurate and efficient method for performing a formal solution is
also presented. A discussion is given of several examples of periodic
media and free-standing slabs, both in static cases and with velocity
fields. For the free-standing slabs, two-dimensional transport effects
are significant near boundaries, but no important effects were found
in any of the periodic cases studied.
